Against all odds, Black Sabbath survived the departure of original frontman Ozzy Osbourne and rose from the grave to create the heralded 1980 album Heaven and Hell with new vocalist Ronnie James Dio. The next year, they proved that lightning could strike twice, and this time they did it without drummer Bill Ward, who struggled from severe substance problems and was replaced by Vinny Appice in the middle of the Heaven and Hell tour. At first, the transition was a major challenge, but gradually the band acclimated to their new drummer.

“I was so used to playing with Bill, it was hard for me,” guitarist Tony Iommi told me in 2009. “I would look at Vinny’s kit and it was a quarter of the size of Bill’s kit. It just looked absolutely ridiculous. He had this little baby kid of drums. And I just went, ‘Fucking hell.’ But Vinny plays really well and I was amazed that he managed to pull it off.”

Unlike Heaven and Hell, which Iommi and Dio wrote in a living room, using small amplifiers while bassist Geezer Butler took time off for personal issues, all three songwriters were there for Mob Rules, which they wrote in a rented studio, with full-sized amps blaring, and which came out November 4, 1981, the same year as Ozzy’s Diary of a Madman and Iron Maiden’s Killers. During the sessions, Butler and Iommi came up killer riffs for both the uptempo songs — the title track and “Turn Up the Night” — and the slower fare, like the bluesy “Voodoo” and the trudging, doomy “Sign of the Southern Cross.” Even so, the sessions were marred by overindulgence and ego battles.

"Mob Rules was a confusing album for us,” Iommi told Guitar World. “We started writing songs differently for some reason and ended up not using a lot of really great material. That lineup was really great but we were still going through drug problems and the whole thing sometimes fell apart for very silly reasons — we were all acting like children."

The sessions might have occasionally fallen apart but in the end, Sabbath were able to put the pieces back together. Considering how strong the priority tracks were, as well as the atmospheric, multi-faceted “Falling Off the Edge of the World,” the Zeppelin-paced “Slippin’ Away” and the almost poppy “Country Girl,” it’s hard to imagine what “really great material” was shelved. And whatever it was, it’s unclear if it was ever used since Mob Rules was Dio’s last studio album with Sabbath until 1992’s Dehumanizer.

Iron Maiden producer Martin Birch produced most of Mob Rules at the Record Plant in Los Angeles, and while he got a great sound out of Sabbath, nearly everyone’s productivity was hampered by excessive drinking and cocaine use — even Birch’s. “When producers get involved in that as well as the musicians it creates problems because the producer is supposed to be the one keeping everyone in line. And that didn’t happen so we felt no need to hold back from what we were doing.”

Fortunately for Sabbath, everyone was skilled enough to create great music despite their inebriation. Other struggles were mostly personal. Butler wasn’t thrilled that he wasn’t writing the lyrics anymore, Dio was. And Iommi was such a perfectionist he was resistant to use anyone else’s ideas. “We definitely had our problems, but we didn’t really argue very much,” Iommi told me. “If we had any serious arguments, that would have been the end. That’s sort of the way it was. There were disagreements but not much yelling. We didn’t let it go there.”

“Attitudes started to change, people were living a bit more high on the hog and it was a lot easier not to be together than it was to be together, perhaps,” Dio told me in 2007. “But it was alright. It wasn’t a nightmare.”

Mob Rules mixed upbeat and trudging songs in a manner similar to Heaven and Hell and Dio’s vocals established a continuity between the two. Boosting the energy level was Appice, who was originally hired to tour with the band and was thrilled to be asked to play on the album as well. “I think everybody was excited,” said Appice. “We jammed a lot and rehearsed live. Tony had riffs, Ronnie had great lyrics and Geezer had good ideas as well and helped put everything together. The thing was like a machine. So there were no times where the page was empty.”

In addition to recording at The Record Plant, Sabbath tracked at the house where John Lennon filmed the video for “Imagine.” “Warner Bros. had a movie called Heavy Metal that they wanted us to do a song for, and we were in England and we needed to record it,” recalled Appice. “We had a couple days off, so we went to the house there, which was owned by Ringo by then. We put the song together in one day, then we started recording that night. We did it all in a couple of days. That was the first recording I did with Black Sabbath and that’s the version that’s on the Heavy Metal soundtrack. We re-recorded it for the Mob Rules album. The arrangement’s the same but it sounds slightly different."

Mob Rules went gold in the U.S. and was received well in the U.K. as well, where “The Mob Rules” and “Turn Up the Night” were both singles. However, some fans criticized the album’s structural similarity to Heaven and Hell and others longed for the glory days when Ozzy was in the band. “We knew that there were going to be people that didn’t like it,” Iommi said. “But for the amount of people that didn’t like it, there were just as many people that liked it. So where we lost some, we attracted others. Some people just want to hear the original lineup, and that’s it. But you can’t always have that. If somebody leaves or if somebody goes, you carry on.”

Black Sabbath’s former publicist Mick Wall, who has written numerous books about Sabbath, Metallica, Guns N’ Roses and others, claims the band was burdened by using the name Black Sabbath. While he said Mob Rules was a solid album – better than the last couple records Sabbath did with Ozzy – it still wasn’t a proper Black Sabbath record.

“It was close,” he said. “If they called it anything else, it would have been one of the all-time great metal albums, but it’s hard for me to see it as a Black Sabbath album. Geezer wasn’t writing the lyrics. And when Ozzy was in the group they seemed to have this weird kind of offensively unhelpful, introverted way of just being themselves, to almost the point of obnoxiousness. There was something obnoxious and arrogant and unfriendly about the music which made it very interesting. And when Dio comes in it becomes slightly more generic and American sounding. It didn’t have that brutish, weird, slightly more British element that they had before that.”

When Iommi, Butler and Appice reunited with Dio under the name Heaven and Hell in 2007 and toured to support the album Black Sabbath: The Dio Years, they routinely played Mob Rules tracks “E5150,” “The Mob Rules,” “Falling Off the Edge of the World” and “Voodoo” and sometimes threw in “Country Girl.” And on the 2014 tribute album Ronnie James Dio – This Is Your Life, Adrenaline Mob celebrated the memory of the late singer with a cover of “The Mob Rules.” The title track has also been covered by Fozzy, Iced Earth and Burning Inside, keeping one of the great Dio/Sabbath albums burning bright.